1. Field of the Invention
This invention relates to neck seals of the type employed on the roll necks of rolls in a rolling mill.
2. Description of the Prior Art
FIG. 1 illustrates a prior art neck seal 10 of the type described in U.S. Pat. No. 4,165,881 (Salter). The seal has a molded flexible circular seal body 12 internally reinforced by an embedded combination of a coiled spring 14 and steel cable 16. The seal body has circular water-side and oil-side lips 18, 20, circular water-side and oil-side flanges 22, 24, and a circular oil flinger 26. When the seal is in the unstressed condition shown in FIG. 1, the water-side lip 18 extends axially from one end of the seal body, the oil-side lip 20 extends angularly inwardly from the seal body, and the flanges 22, 24 extend radially from the body in perpendicular relationship with respect to the seal axis schematically depicted at "a". The flanges 22, 24 are axially separated by a cylindrical exterior surface 28, and each flange is provided with a peripheral flexible lip 30 extending angularly outwardly from a heel portion 32.
As shown in FIG. 2, the seal 10 is adapted to be mounted on the tapered section 34 of a rolling mill roll neck 36 which in turn is rotatably supported in an oil film bearing. The bearing includes a sleeve 38 fixed to the roll neck by conventional means (not shown) for rotation therewith. The sleeve 38 has an outer cylindrical bearing surface which is journalled for rotation within an interior bearing surface of a fixed bushing 40. The bushing is carried in a bearing chock 42.
The sleeve rotates with the roll neck while the bearing chock and the bushing remain stationary. Oil in flooding quantity is fed continuously between the bearing surfaces of the sleeve 38 and bushing 40. A circular extension 44 of the bearing chock provides a sump 46 in which the oil emerging from between the bearing surfaces is continuously collected. The oil may be drawn away from the sump through a suitable piping connection (not shown) to be cooled and filtered before being recycled back to the bearing surfaces.
Where the roll is operating under "wet" conditions, water is constantly flooding over the roll barrel 48 and down over its end face 50. In spite of the centrifugal forces which tend to throw the water off of the roll, some of the water tends to work its way along the roll neck in the direction of the bearing. The objective of the seal assembly generally indicated at 52 and the flexible neck seal 10 which forms a component part thereof is to prevent any of the water from infiltrating into the bearing and contaminating the bearing oil while at the same time preventing loss of oil from the bearing.
In addition to the flexible seal 10, the seal assembly 52 includes a rigid circular seal end plate 54 which is mounted on and fixed relative to the roll chock 42. The seal end plate has a radially inwardly extending rigid circular flange or "dam" 56 which is perpendicular to the bearing axis. The inner edge of the dam is spaced radially from the exterior cylindrical surface 28 on the flexible seal body. The seal end plate further includes shoulders 58 extending in opposite directions from the base of the dam 56. Each of the shoulders 58 has a cylindrical shoulder surface 60 which is parallel to the bearing axis. The cylindrical shoulder surfaces 60 surround the flexible seal flanges 22, 24, and are arranged to be slidingly contacted by the flexible lips 30.
The seal assembly 52 also includes an inner seal ring 62 with resilient buttons 64 engaging the end face 50 of the roll. The inner edge of the inner seal ring contacts the flexible seal body 12 at the juncture 66 of the lip 18 and flange 22. An outer seal ring 68 surrounds the inner seal ring 62. A metal reinforcing band 70 encircles the cylindrical outer surface 28 of the seal body 12.
During a rolling operation, the above-described arrangement will operate in the following manner: the inner seal ring 62, flexible neck seal 10 and sleeve 38 will rotate with the roll neck. The outer seal ring 68, seal end plate 54, chock 42 and bushing 40 will remain stationary. Lubricating oil will constantly flow from between the bearing surfaces of the sleeve 38 and bushing 40. Most of this oil will be turned back by the rotation flinger 26 on the neck seal and will thus be directed to the sump 46. Oil which succeeds in passing by the flinger 26 will be turned back by the rotation oil-side flange 24 and will be prevented from escaping between the flange 24 and the shoulder surface 60 by the flexible lip 30 which sealingly engages the shoulder surface. Likewise, the major portion of the water applied to the roll will be turned back by the rotating inner seal ring 62. Any water which succeeds in passing by the inner seal ring will be turned back by the rotating water-side flange 22 on the neck seal and will be prevented from passing between the flange and its surrounding shoulder surface by the flexible lip 30.
Although the above-described arrangement operates in a generally satisfactory manner, experience has indicated that when the seal is mounted on the tapered roll neck section 34, the seal body is radially stressed and the water-side lip 18 is radially expanded. Radial expansion of the lip 18 subjects the seal body to a circumferential bending moment M.sub.1 which tends to distort the water-side flange 22 from its relaxed perpendicular orientation with respect to the seal axis as illustrated in FIG. 1, to the angularly distorted position shown in FIG. 2. Thus, as the roll 48 undergoes axial shifting to the right as viewed in FIG. 2, the angular disposition of the flange 22 causes its heel 32 to come into frictional contact with the dam 56 of the seal end plate 54. This can lead to premature wearing of the flange 22 in the region of its heel 32, which in turn can cause leakage.